Objectives: To evaluate High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM) as an adjunct to usual care for individuals with traumatic brain injury (TBI). TBI may be followed by heterogeneous symptoms including depressed mood, impaired sleep, post-traumatic stress, and others, many associated with autonomic dysregulation. Studies of brain electrical activity in TBI report suboptimal proportionation between high and low frequencies, and PTSD, often seen with TBI, has been associated with right temporal lobe over-activation. HIRREM generates feedback as audible tones derived from software algorithm-driven analysis of real time changes in brain electrical activity from scalp recordings, measured at high-spectral resolutions, to facilitate auto-calibration of neural oscillations.

Methods: Twenty-one subjects (mean age 34.7, range 15-64, 9 women) reporting symptoms relevant to prior TBI (related to sports for 6, to military service for 5) were enrolled in an IRB-approved, open label feasibility study of HIRREM for diverse clinical conditions. Subjects had a baseline HIRREM assessment followed by a median of 16 (range 10 to 36) HIRREM sessions (90 minutes each) over a median of 13 days (range 9 to 93). Temporal high frequency electroencephalic asymmetry scores (percentage basis) were calculated at baseline and for serial HIRREM sessions by measuring one minute epochs of high frequency (23-36 Hertz) amplitudes (microvolts) at bilateral temporal lobes (T3/T4), subtracting the value at T3 from that at T4, and dividing by the lesser of the two (yielding positive scores for right dominance). Blood pressure and heart rate were measured during recordings at baseline and after completion of the final HIRREM session, to assess cardiovascular autonomic regulation including heart rate variability (HRV).

Results: After completing HIRREM, subjects on average reported reduced symptoms of insomnia (pre to post-HIRREM change in the Insomnia Severity Index of 13.7 to 7.1, p<0.0001), depression (change in CES-D of 24.3 to 12.7, p<0.0001), and symptoms of post-traumatic stress (change in PCL-C of 44.7 to 32.7, p=0.0001). Measures of HRV improved after HIRREM (SDRR increased from 51.8 to 65.2ms, p=0.009). In subjects (n=8) who were initially right-temporal (T4) dominant (amplitudes ≥10% rightward), temporal asymmetry changed from a median of 49.7% to -2.5% (p=0.06). In those who were initially left-temporal (T3) dominant (n=9), asymmetry scores changed from a median of -30.4% to 18.9% (p=0.0004). For those who were initially <10% asymmetrical in either direction (n=4), asymmetry changed from a median of -4.0% to -14.9% (p=0.75).

Conclusions: In this case series, use of HIRREM by individuals with prior TBI was associated with statistically significant reductions in clinical symptoms of insomnia, depression, and post-traumatic stress, and increased HRV. Trends were found for reduced temporal asymmetry among those who were ≥10% asymmetrical at baseline. Controlled clinical trials of HIRREM for TBI are warranted.